This project concerns the correlation of gonadal hormone titers with differences in mating behavior; the effects of copulation on the endocrine system; and the site and mode of androgen action on male behavior. Using radioimmunoassay, to measure circulating hormone levels, we are determining whether any features of the individual variations in patterns of mating behavior can be correlated with plasma testosterone in the male and ovarian steroids in the female. Hormone-behavior relationships are being studied during development, and the latency of effects of testosterone and progesterone on male and female sexual behavior respectively will be precisely determined. Possible behavioral consequences of effects of mating and stress on testosterone secretion will be evaluated. The respective roles of androgenic stimulation of the brain and of the genital tissues will be evaluated in terms of their relative importance in male couplation. BIBLIOGRAPHIC REFERENCES: Davidson, J.M. Reproductive behavior in a neuroendocrine perspective, In Lehrman Memorial Symposium on Reproductive Behavior. (in press, 1975-76). Davidson, J.M. and S. Trupin. Neural mediation of steroid-induced sexual behavior in rats. In Sexual Behavior: Pharmacology and Biochemistry. Sandler, M. and Gessa, G.L. (eds.) Raven Press, New York, N.Y. 1975.